Comparative studies of the structures and transition characteristics of cellulose diacetate modified with polyethylene glycol prepared by chemical bonding and physical blending methods

Phase change materials (PCMs) of cellulose diacetate (CDA) modified with polyethylene glycol (PEG) prepared by chemical bonding and physical blending methods exhibit different characteristics: Chemically bonded materials exhibit typical solid-solid phase change characteristics, but the blended materials exhibit solid-liquid phase change characteristics. In all these materials, CDA is the framework, and PEG is a working substance that gives and takes in latent heat during its melting and crystallizing process. For the chemically bonded materials, the bonding strength is strong enough to ensure that no PEG is detached, so even at a high temperature (i.e., above the melting temperature of PEG), the material still remains in the solid state. In contrast, for the blends, at high temperature the amorphous PEG can migrate freely within the CDA framework and may escape to the surface of the blends through a diffusion mechanism.